The present invention relates to sand-control apparatus and methods in a subterranean hydrocarbon well. More particularly, the present invention relates to methods and apparatus for using an expandable sand control device in conjunction with a specialized gravel pack fluid system.
The control of the movement of sand and gravel into a wellbore and production string has been the subject of much importance in the oil production industry. Gravel pack operations are typically performed in subterranean wells to prevent fine particles of sand or other debris from being produced along with valuable fluids extracted from a geological formation. If produced, the fine sand tends to erode production equipment, clog filters, and present disposal problems. It is therefore economically and environmentally advantageous to ensure that the fine sand is not produced. During gravel packing, the annulus between the well bore wall and the production tubing, which can include a screen or slotted liner assembly, is filled with selected natural or man-made packing material, or xe2x80x9cgravel.xe2x80x9d Such packing materials can include naturally occurring or man-made materials such as sand, gravel, glass, metal or ceramic beads, sintered bauxite and other packing materials known in the art. The gravel prevents the fine sand from the formation from packing off around the production tubing and screen, and the screen prevents the large grain sand from entering the production tubing.
One difficulty in packing operations, especially in open-hole wellbores, is completely filling the often irregular annular space between the production tubing and the wellbore wall. Where packing is incomplete, xe2x80x9cvoidsxe2x80x9d are left around the production tubing. These voids, or areas which are incompletely packed with gravel, allow sand fines to be produced along the area of sand screen or slotted liner. The fines can clog the production assembly or erode production equipment.
Consequently, a more effective method of packing a wellbore is needed.
In general, a method is provided for completing a subterranean wellbore, and an apparatus for using the method. The method comprises positioning an expandable sand-control device in the wellbore thereby forming an annulus between the sand-control device and the wellbore; depositing a filter media in the annulus; and after the depositing step, radially expanding the sand-control device to decrease the volume of the annulus. The sand-control device can be a sand screen or slotted or perforated liner having radially extending passageways in the walls thereof, the passageways designed to substantially prevent movement of the particulate material through the passageways and into the sand-control device. Where a slotted liner is desired, the passageways can be plugged during positioning and later unplugged for production.
The filter media is typically a particulate material and can be deposited as a slurry comprising liquid material and particulate material, or as a cement slurry. The step of expanding the sand-control device further includes squeezing at least a portion of the liquid of the slurry through the sand-control device passageways thereby forming a pack in the wellbore annulus. The liquid material can be water-based, oil-based or emulsified and can include gelling agents. Further, the particulate can be resin coated with a delayed form system. The form system can include particulate material. The foam can also include decomposable material which can be decomposed after placement of the form in the annulus.
Another embodiment of the method and apparatus presented herein comprises positioning a well-completion device into the wellbore, thereby forming an annulus between the well-completion device and the wellbore, the well-completion device having a flexible, permeable membrane sleeve surrounding an expandable sand-control device; and thereafter radially expanding the sand-control device to decrease the volume of the annulus, thereby also expanding the membrane sleeve. The well-completion device can further include a layer of filter media encased between the membrane sleeve and the sand-control device. The filter media may be of any type known in the industry. Preferably, the membrane sleeve, when expanded, substantially fills the annular space extending between the wellbore and the sand-control device by deforming to substantially contour the wellbore.